The present invention relates to a fuel cell system, more particularly to a fuel cell system capable of shortening a starting time.
This kind of the fuel cell system is an apparatus to convert energy of a fuel to electric energy directly, and supplies hydrogen rich gas to a cathode (fuel electrode) side of a pair of electrodes, each of which is provided so as to interpose an electrolytic film therebetween. At the same time, the fuel cell system supplies oxygen-containing gas such as the air to an anode (oxidizing agent electrode) side thereof. Thus, the fuel cell system utilizes the following chemical reactions, which occur on surfaces of the pair of the electrodes, which face the electrolytic film, thus taking out the electric energy from the electrodes (refer to Japanese Patent Laid-Open No. H8-106914).
Cathode reaction: H2xe2x86x922H++2exe2x88x92
Anode reaction: 2H++2exe2x88x92+(xc2xd)O2xe2x86x92H2O
As an apparatus for generating hydrogen rich gas serving as an electromotive fuel, a reformer, which performs a steam reforming of methanol to convert the methanol into fuel gas containing hydrogen abundantly, is used. As an apparatus for generating oxidizing agent gas containing oxygen, a compressor, which takes in air to produce the compressed air, is used. While supplying the compressed air to the anode of the fuel cell after cooling the compressed air from the compressor by an after cooler, methanol gas is fed to the reformer from a fuel tank, and the hydrogen rich gas reformed by the reformer is supplied to the cathode of the fuel cell.
Since the fuel cell system is more advantageous in terms of a gas mileage and conditions for preparing infrastructures for fuels than an electromobile driven by a secondary cell, an adoption of the fuel cell system to a driving power source for use in an automobile is considered.
However, to adopt the fuel cell system to the driving power source for use in the automobile, the shortening of the starting time is one of subjects to be solved, and how to generate hydrogen rich gas quickly is particularly a question.
A fuel cell system disclosed in Japanese Patent Laid-Open No. H11-86893 aims at shortening of a starting time of a reforming apparatus. This gazette proposes a technology in which in starting the system, reforming fuel fed by a fuel pump is burnt by the use of a burner, and an evaporator for evaporating the reforming fuel, followed by rising temperature of a reforming heat portion by exhaust gas. At this time, to rise the temperature of the reforming heat portion quickly, a technology is also proposed, in which the fuel is supplied to the burner excessively or the fuel is directly sprayed to the heat portion for heating a reforming portion by the exhaust gas via a nozzle, a catalyst is coated on a surface of a case of the heat portion, and the fuel is burnt on the surface of the case thereof, thus rising temperature of the reforming portion from the outside by heat generated by burning the fuel.
However, in this fuel cell system, the burner is first started and the temperature thereof is risen, and the evaporator is heated to a higher temperature by combustion gas from the burner. Thereafter, the reforming portion is heated by the combustion gas. Accordingly, since such starting procedures are adopted, that is, since the temperature of the reforming portion is risen after the rise of the temperatures of the burner and the evaporation, there is a problem that the starting time is taken longer by a time required for the reforming portion to rise its temperature.
The present invention has been made in view of the problems of the earlier technologies, and the object of the present invention is to provide a fuel cell system capable of more shortening the starting time.
To achieve the above-described object, a fuel cell system of the present invention is provided with a reformer generating hydrogen-containing gas used for starting fuel, wherein reforming fuel and oxidizing agent are first supplied to the reformer in starting the fuel cell system, and a rise in temperature is started in response to a partial oxidation reaction of the hydrogen-containing gas with the reforming fuel and the oxidizing agent.
In other words, a fuel cell system of the present invention is provided with reforming means for generating hydrogen-containing gas used as starting fuel, wherein reforming fuel and oxidizing agent are first supplied to said reforming means when said fuel cell system is started, and a rise in temperature is begun by a partial oxidation reaction of the reforming fuel and the oxidizing agent.
Beside, a method of controlling a fuel cell system having a reformer which generates hydrogen-containing gas used as starting fuel of the present invention produces first supplying reforming fuel and oxidizing agent when said fuel cell system is started and beginning a rise in temperature by a partial oxidation reaction of the reforming fuel and the oxidizing agent.
The partial oxidization reaction equation of the present invention is as follows:
CH3OH+xc2xdO2xe2x86x922H2+CO2+189.5 KJ/mol.
The self-heating of this partial oxidization reaction makes it possible to rise the temperature of the whole of the reforming system and to start the reforming system in a short time. As a result, shortening of the starting time of the fuel cell system can be achieved.
Note that, at this time, a heat value can be further increased by making the ratio of the supplied oxidizing agent to the reforming fuel larger than that at a normal operation.